Depends: the candle might add a little heat. When it catches your tent and sleeping bag on fire, it will add a lot of heat, briefly. Then it will get much colder.

A safer, surer, and more versatile method to add warmth to a tent is to take along an extra layer (or use an insulated layer in place of fleece.) The key isn’t to warm up the interior of the tent, it’s to insulate your body to retain the heat you produce. You can wear extra/warmer clothing inside or outside your sleeping bag to add warmth.

If you only get cold in your tent, inside your sleeping bag, then the better investment may be to upgrade to a 10-degree-warmer bag. Also, if you only get cold on the side closest to the ground, check the r-value of your sleeping pad. In the Ohio Valley, a 3+ r-value (example: Thermarest Prolite Plus) works as a winter pad above 25 degrees or so. Below that, I use an r-5 Neoair All-Season. The Neoair, plus wearing Western Mountaineering down jacket, pants, and booties inside a WM 20-degree bag, kept me toasty on an unexpected 5-below night once, with about an inch and a half of snow under the Hubba tent I was using.

I really can’t caution you enough not to use a candle, especially an open flame, inside your tent. Even inside a candle lantern, the glass and wire bail get hot enough to melt, and possible ignite, tent material. I saw a tent go up in flames once in a nearby campsite; it was impressive and scary at the same time. The culprit was an open flame from a knocked-over candle.

Im geared to 0 degrees. I brought up that that i took a tent on a backpacking trip last week instead of my tarp on a fb ul page. Its doubled walled. I had condensation on my quilt in the mornings. A few toldme they used these candles to stop the condensation and that it also added warmth

The folks who told you that are correct: additional heat will minimize condensation and add a little heat - until the candle burns out, then it probably takes about 5 minutes for the condensation to return with a vengeance (the warm air will hold more water vapor than cold air; the additional vapor will have come from your breath.)

However, what those folks didn’t tell you (probably because they’ve been very lucky, or didn’t want to admit they burned a tent down) is that the safety risk is HUGE, especially if you fall asleep with the candle lit, and move around and knock it over in your sleep.

I’m strongly discouraging you from trying this; the safety risks are too high, and far outweigh any small benefit. This isn’t a traditional v. UL argument; the UL folks who encourage this are, in my opinion, what some of us call “stupid-light.” You can also minimize condensation by venting your tent a little bit: leave the vestibule slightly open, and use any ceiling vents you have.

I’ve never used a candle or other open flame (or enclosed flame, for that matter) inside a tent, and don’t intend to start.

Im geared to 0 degrees. I brought up that that i took a tent on a backpacking trip last week instead of my tarp on a fb ul page. Its doubled walled. I had condensation on my quilt in the mornings. A few toldme they used these candles to stop the condensation and that it also added warmth

If you didn't have condensation dripping from the walls of the tent, then the condensation was coming from you, in a manner of speaking. If you bring a light covering for your sleeping bag in such a situation, the condensation should travel to that and stay off of your bag, FWIW. And, anyway, many quilts/bags have a DWR outer, so a bit of condensation on the top isn't too much to worry about, just wipe/brush it off with a rag/bandana/etc.

Also, any such combustion produces carbon monoxide. Not good, and the more your tent is 'buttoned up' the worse that is.

Since you live in Texas and do some backpacking in Arkansas you might want to check out the campfire tent I made. It's based on the bushcrafter's "Super Shelter" design but made for backpacking. It's pretty easy to make too.

I've played with the candle heater concept a bit using tea candles and small disposable foil baking pans. I used 3 candles burning inside the tent, but I really cannot recall for sure how much gain in temp I got. I do recall it wasn't near as much as a campfire like the one in the video, but it was enough to demonstrate it works.

But that was an afterthought and this tent wasn't designed for that and doesn't have the room inside to fall asleep with one going so I've never tried it while camping. But it does demonstrate how to capture radiant heat and that's one of the keys to making it work.

So I believe is worth working on and using this reflective material one should be able to design something that's optimized for a candle heater. I was thinking something more like a bivy tent so you have less space to heat, maybe with an extended end at the head or foot to place the heater, perhaps behind a net to protect it (and me).

You need something to capture and radiate the heat from the candle too. As I recall, I used a rock with one of my tests, which we have in abundance here. My theory was the rock would store the heat and radiate more efficiently but it took forever to heat it up so that wasn't a good choice. A piece of aluminum sheet would work pretty good though, something the thickness of a cookie sheet would be durable enough.

I'm sure it can be done safely with good design and common sense. I've spent quite a few nights in my campfire tent all cozy and warm and wouldn't use anything else here now when it's cold out. But I would use one heated with candles.